SAP Customizing of the Index Pool
Settings have to be made in SAP standard Customizing for both index pools:

It is already possible to set the percentage in the table, but this percentage is not yet evaluated by the program in Releases 4.6B and 4.6C.
These settings are stored in the Customizing table TSADRVGRPC. This table is maintained as of Release 4.6C in the IMG under Basis Components ® Basis Services ® Address Management and as of SAP Web Application Server 6.10 under
SAP Web Application Server ® Basis Services ® Address Management.
Transaction SM30 with view V_TSADGRPC has to be called to maintain the settings in Release 4.6B.